Implement automatic load of composed/embedded automation trees

chrome/browser/accessibility/ax_tree_id_registry.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_
+#define CHROME_BROWSER_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_
+
+#include <map>
+
+#include "base/stl_util.h"
+
+template <typename T>
+struct DefaultSingletonTraits;
+
+// A class which generates a unique id given a process id and routing id.
+// Currently, placeholder implementation pending finalization of out of process
+// iframes.
+class AXTreeIDRegistry {
+ public:
+  typedef int AXTreeID;
+  typedef std::pair<int, int> FrameID;
+
+  // Get the single instance of this class.
+  static AXTreeIDRegistry* GetInstance();
+
+  // Obtains a unique id given a |process_id| and |routing_id|. Placeholder
+  // for full implementation once out of process iframe accessibility finalizes.
+  int GetOrCreateAXTreeID(int process_id, int routing_id);
+  FrameID GetFrameID(int ax_tree_id);
+  void RemoveAXTreeID(int ax_tree_id);
+
+ private:
+  friend struct DefaultSingletonTraits<AXTreeIDRegistry>;
+
+  AXTreeIDRegistry();
+  virtual ~AXTreeIDRegistry();
+
+  // Tracks the current unique ax frame id.
+  int ax_tree_id_counter_;
+
+  // Maps an accessibility tree to its frame via ids.
+  std::map<AXTreeID, FrameID> ax_tree_to_frame_id_map_;
+
+  // Maps frames to an accessibility tree via ids.
+  std::map<FrameID, AXTreeID> frame_to_ax_tree_id_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(AXTreeIDRegistry);
+};
+
+#endif  // CHROME_BROWSER_ACCESSIBILITY_AX_TREE_ID_REGISTRY_H_